Method and apparatus for improving the texture of hollow metal bodies



Dec. 1, 1931- F. c. LANGENBERG 1,834,128 METHOD AND APPARATUS FOR IMPROVING THE TEXTURE OF HOLLOW METAL BODIES Filed Dec. 29, 1928 2 Sheets -Sheet l a w HM X K w Q N b N Inventor fiedejokafiazyerzbery Wil 133/ z D 1, 1931- F. c. LANGENBERG 1,834,128

METHOD AND APPARATUS FOR IMPROVING THE TEXTURE OF HOLLOW METAL BODIES Filed Dec. 29, 1928 2 Sheets-Sheet 2 Inventor Patented Dec. 1, .1931

, UNITED STATES PATENT OFFICE T'BEDERICK 0. LAN GENBEBG, O! N EW YORK, N. Y ASSIGNOB TO UNITED STATES CAST IRON PIPE & FOUNDRY COMPANY, OI BURLINGTON, JERSEY, A. CORPORATION OF NEW JERSEY METHOD AND APPARATUS FOR IMPROVING THE TEXTURE OF HOLLOW IETAL BODIES Application fled December 28, 1928. Serial No. 829,208.

as resistance to wear, of the metal. My in-- vention is especially applicable to hollow steel bodies of a generally cylindrical form and 5 has been found of a special value as applied in the manufacture of steel molds for the centrifugal casting of tubes. The application of my invention, however, to the manufacture of centrifugal steel molds and particularly to the manufacture of new molds from used steel molds which have become useless by reason of the roughening of their inner surfaces forms the subject matter of a separate application for Letters .Patent,

filed December 29, 1928 Serial No. 329,189, for which Letters Patent No. 1,7 53,747 were 7 anted A ril 8, 1930, my present a p icaan being intended to cover broadly the application of my invention in the manufacture of any metal structures and the essential features of an; apparatus such as must be provided for the practice of my process. p The nature of my improvements will be best understood as described in connection with the drawings, in which Figure 1 is a sectional elevation of an apparatus designed for the application of my process, said view showing a tubular steel 40 mold located in the apparatus in position to be operatedupon a mandrel upon which the blank is to be compacted, packing rings located to confine the fluid under pressure and a special arrangement by means of which the fluid under pressure is made to exert both 1, in which the packing is so held that it oes not subject the mold or blank to a direct longitudlnal stress, and Y Flgure 3 is a sectional elevation showing a modification of the apparatus in which the mold or blank here shown as of cylindrical form throughout is permitted to expand longitudinally in both directions.

Referring first to Figure 1, A indicates the container whichmust, of course, be of great strength to withstand the pressure to WhlCh it is subjected. A indicates the inside of the container; a an enlargement at the right hand end of the container adapted to receive the bell end of a pipe mold andA a con- 'dult passage for fluid under pressure. B is an end plate firmly secured to the right hand end of the container. C is a mandrel which is located inside of the mold or blank to be operated on and upon which said mold or blank is compacted, .0 indicating an enlarged end of this mandrel which, as shown fits in the outer portion of the bell end 0 the mold under treatment. D indicates the mold or blank, here shown as an already formed centrifugal steel mold which, by my process, is to be readially contracted and simultaneously longitudinally expanded by the fluid pressure to' which it is subjected. D indicates the ,bell end of this mold and D, D, indicates circumferential slots formed at the spigot end of the mold, such as are usually provided to receive packing rings when the mold is in use. 1) indicates the inner surface of the mold which, in cases where the blank under treatment is a used .mold, will become cracked and roughened. E indicates a packing ring fitted between the enlarged portion a of the container and the bell end of the mold, the packing ring being shown as 5 resting against a retaining ring F and as having a wide spreader, as indicated at G, inserted in the U-shaped packing ring. H, H, indicate rings which are located in the circumferential slots D. I, a block resting against the rear ring H and F a block resting against the forward ring H and against the end of the ringI and F is a packing ring resting against the block or ring F.

In operation the blank or mold is placed 1n the container as indicated with the mandrel C in position as shown and with the packing rings F and F fitted between the inside of the container and the outside of the blank or mold and supported in position by the devices which I have described; the parts being assembled, fluid under pressure is ad mited through the port A and acting on the outside of the mold or blank radially contracts said blank and at the same time longitudinally elongates the blank and, in the construction of Figure 1, this elongation of the blank which will take place by the mere pressure exerted on the outside of the blank when it is radially contracted is facilitated by the direct application of the pressure through the packing ring F and the supports of said packing ring to the spigot end of the mold or blank. Care must be taken, however, that the area of the packing ring F exposed to the fluid pressure is not so great as to exert an undue longitudinal stress on the blank as, otherwise, there may be a tendency to tear the blank in two. The pressure should be only such as will facilitate and aid in the elongation of the blank.

The effect of the radial. contraction and longitudinal expansion of the blank is both to compact and change the form of the crystals or component elements of the metal in such a way as to materially increase its density, strength and hardness.

Referring to the modification shown in Figure 2: in the construction here indicated, the container is provided with an end plate J, against which abuts a follower, indicated at K, on which again rests the ring indicated at F which directly supports the packing ring indicated at E With this construction the packing ring E exerts no longitudinal stretching force upon the mold or blank, a longitudinal expansion of which takes place purely by the circumferentially applied fluid pressure.

In the modification shown blank indicated at D, D, is of cylindrical form and followers K and K are provided at both ends of the container to su port the packing indicated at E and .E. l y means of this construction the fluid pressure applied to the blank not only contracts the blank upon the mandrel but effects a longitudinal expansion of the blank in both directions.

It will "be understood, of course, that many of the advantages of my invention can be in Figure 3, the

availed of by contracting a blank to a certain definite extent regulated by the amount of fluid admitted to the container and without the use of a mandrel although obviously the mandrel is a highly desirable feature of the construction, both in limiting the contraction of the blankand in delimtely forming its interior surface.

l have found it advantageous to subject the cylindrical body after contraction and elongatlon to a low heat treatment, between 200 U. and 400 (3., such treatment doubtless relieving some interior strains but notably increasing the hardness and wearing qualities of the metal. The temperature to be employed will naturally vary with the nature of the metal; those I have instanced relate to ordinary commercial steel.

For the successful application of my method, it is necessary that the wall thickness of the cylindrical body under treatment should be suflicient to prevent the liability ofthe body to crumple instead of radially contracting under the influence of the l'lllld. pressure applied to its exterior. The necessary wall thickness. to obviate this liability will vary somewhat with the diameter of the cylindrical body under treatment but, as an example, I may say that with a steel tube of two inches internal diameter, the wall thickness should not be less than one thirty-second of an inch.

While my new method is, I believe, most usefully applied steel bodies, I have also found it useful as applied to hollow bodies of brass and bronze and the improvement in the structure of the metal is noticeable with such metals, but while I believe such structural improvement will always follow my treatment, it will be understood that my invention has value as a forming process apart from such improvement.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. The method of changing the form and improving the metallic structure of tubular metal b0(l16S of a generally cylindrical form which consists in securing suchbodies in high pressure container in such manner t the tubular body is free to expand lon' dinall therein and subjecting the ext cylin rical surface of the entire portion of the body to be operated upon to the simultaneous application of hydraulic pressure suflicient in amount to effect a permanent radial contraction and resultant simultaneous lon itudinal elongation of said cylindrical body.

2. The method of claim 1 in which the deformation of the hollow body is aided by subjecting it to a longitudinally acting stretching force.

3. The method of claim 1 in which the deformation of the hollow body is limited by contracting it upon a mandrel.

to the treatment of hollow 4. Apparatus for radially contracting and longitudinally elongatin hollow metal bodies of a generally cylin rical form consisting of a container, means for supporting a. hollow metal bod therein, includin packings adapted to orm fluid tight joints between the container and both ends of the hollow metal body and means for introducing fluid under pressure to said container at a point between the said packings.

5. Apparatus as called for in claim 4, having a mandrel supported thereon to give final form to the metal body.

6. Apparatus as called for in claim 4, in which a packing ring is anchored to an end of the metal body so as to act as a piston imparting a longitudinal pull thereto.

FREDERICK C. LANGENBERG. 

